Use of organic fibre cement as a raw material in the production of cement clinker

Fiber cement material, which contains organic fibers, is used as an additional raw material for the production of cement clinker. The cement clinker is produced in a system which comprises a cyclone tower (11) and a rotating drum kiln (15). The cyclone tower (11) comprises cyclones (1-5) and a pre-calciner unit (10) wherein fuel is combusted to feed the cyclone tower with heat. The raw clinker meal is passed through the cyclone tower to preheat it. By the combustion of the fuel in the pre-calciner unit (10) a hot zone is produced in the cyclone tower wherein the raw clinker meal is calcined. In order to be able to add larger amounts of the fiber cement material without causing a too high total organic carbon content of the exhaust gasses and/or without causing depositions of organic matter onto the inner walls of the cyclone tower (11), the organic fiber cement material is added in a dry powdered form in said hot zone, in particular in the pre-calciner unit (10) to be heated in less than 5 seconds to a temperature of at least 800° C.